Bug #19338: Ruby hangs when ouputting warnings inside ractor with VM lock held

• Status: Assigned
• Priority: Normal
• Assignee: ko1 (Koichi Sasada)
• Target version: -
• Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN

[luke-gru (Luke Gruber)]

This code causes Ruby to hang:

rs = []
2.times do
  rs << Ractor.new do
    MYCONSTANT = 2
  end
end
rs.each(&:take)

There is a problem when the warning is being outputted with multiple ractors. A thread is calling RB_VM_LOCK() while holding the VM lock in ractor.c (ractor_check_blocking())

If the code is changed to RB_VM_LOCK_ENTER() and RB_VM_LOCK_LEAVE() then it fixes it, but I don't know if there's a better way.

Thanks!

[luke-gru (Luke Gruber)]

• Subject changed from Ruby hangs when defining new constant in ractor to Ruby hangs when ouputting warnings inside ractor

[luke-gru (Luke Gruber)]

To simplify the problem, this hangs too:

MYCONSTANT = 1
Ractor.new do
  MYCONSTANT = 2
end.take

[luke-gru (Luke Gruber)]

• Subject changed from Ruby hangs when ouputting warnings inside ractor to Ruby hangs when ouputting warnings inside ractor with VM lock held

[hsbt (Hiroshi SHIBATA)]

• Status changed from Open to Assigned
• Assignee set to ko1 (Koichi Sasada)